Mixing machine for concrete or similar material



Jam 1955 F. L. VAN DAELEN 2,698,741

MIXING MACHINE FOR CONCRETE OR SIMILAR MATERIAL Filed June 30, 1952 2 Sheets-Sheet 1 IN V EN TOR. l ll x lay/Is Mari/k Van fiaelerz 1955 F. L. M. VAN DAELEN 2,698,741

MIXING MACHINE FOR CONCRETE OR SIMILAR MATERIAL Filed June 30, 1952 2 Sheets-Sheet 2 INVENTOR. Z2511? [oz/A9 flZYr/e 16/7 kale/z United States Patent MIXING MACHINE FOR CONCRETE OR SIMILAR MATERIAL Felix Louis Marie van Daelen, Amsterdam, Netherlands Application June 30, 1952, Serial No. 296,403

Claims priority, application Netherlands July 9, 1951 6 Claims. (Cl. 259165) The invention relates to a mixing machine for concrete or similar material in which the components, more particularly gravel, sand and cement, are red by separate dosage devices in dosed quantities to a horizontal rotating mixing drum provided internally with rixed partition walls forming a helical passage, and are mixed with water.

Such machines are known. They did not satisfy in practice because the cement and sand adhere to the wall of the mixing drum, whereby a separation of the gravel takes place. indeed from time to time lumps of the material adhering to the wall of the mixing drum will get loose, but these lumps contain practically no gravel and still further disturb the mixing proportion. For countering this defect it has already been proposed to arrange knocking devices working on the drum wall. The result of such knocking devices, however, is uncertain, so that with such devices the defect can only in part be met and can be counteracted in an irregular manner. Therefore in practice deviations from the desired mixing proportion are obtained, which can amount up to 36%.

The invention now aims at providing a mixing machine in which adhesion of cement and sand can be fully avoided or in any way can be limited to a predetermined minimum and therefore a very good constant mixing proportion and at the same time a very good mixing, also for very dry concrete mixtures, can be obtained.

According to the invention this is obtained by that the wall of the mixing drum is formed by a flexible band which is passed over a stretching roller arranged above the mixing drum, so that the upper portion of the mixing drum is open. Preferably the flexible band is executed by an endless conveyor band with rubber covering. In this manner a mixing device is obtained in which, by that the wall of the drum is differently bent on the drum and on the stretching roller, the adhesion of cement and sand is already hindered to a high degree, but at the same time it becomes possible to arrange in the space between the mixing drum and the stretching roller a scraper fillet extending on the whole width of the drum in axial direction and cooperating with the part of the flexible band leaving the drum, so that cement and sand adhering to it can be scraped 0E. The scraping mechanism does not need to be continuously in contact with the band, but for instance it can be adjusted lying on a very small distance from it, so that the layer of adhering material in any way can be limited to a predetermined minimum, without causing wear of the band.

Further the use of the flexible band enables the arrangement of a water supply means extending in axial direction in the space between the mixing drum and the stretching roller, which sprays the water against the part of the flexible band leaving the mixing drum. Also by this measure adhesion of material can be prevented to a high degree, while at the same time the spraying means can be executed in such manner that the upper edge of the material lying in the drum is moistured 'and thereafter it is carried down by the rotation of the drum, so that the supplied water comes always in contact with a new layer of the mixture. Appropriately the water supply means is arranged in the direction of the movement of the flexible band before the scraper mechanism.

The machine according to the invention further enables the execution of the water supply means as a spraying pipe lying in axial direction, which extends only on the last part of the mixing drum till the delivering end. in this way the material can first be mixed in a dry condition and can then be brought in touch with water. This has as a result that also extremely dry concrete mixtures can be prepared with great certainty of a constant and uniform mixture.

for obtaining the constant mixing proportion it is at the same time necessary that the dosage devices for the components also have a constant and uniform dosage and delivery. in this connection appropriately the dosage device for the cement is formed by a vane wheel rotatably mounted on a vertical spindle and having rectangular vanes moving at the bottom side along a fixed bottom plate and tippable round radial spindles with respect of which they can be arrested and above which vanes a striking plate is arranged which is adjustable in axial direction and extends about on three compartments formed between the vanes and under the middle or which an outlet opening is present in the bottom plate having about the dimensions of one of the compartments. Such a dosage mechanism is very accurately adjustable and enables the dosage of the cement in such a manner that in the dosage mechanism no material is left, so that a constant dosage is guaranteed. For the ad ustment the radial spindles of the vanes or the vanes are appropriately each provided with a transverse arm at the ends lying near the spindle, which transverse arms cooperate with a sleeve or cap, which is ad ustable and can be fixed with respect of the spindle and/or with respect of the carrier of the vane spindles. In consequence the vanes can be adjusted all simultaneously and to the same degree.

The dosage device for the gravel and/or the sand is appropriately formed by a star-shaped member mounted on a horizontal spindle and consisting of adjustable partitions hinged between round disc shaped side walls which are mutually fixed by a sleeve, the adjustment of the partitions taking place by rotating the spindle, which is coupled by levers with the partitions with respect of the member in which the partitions are arranged. Appropriately the filling opening for the sand or the gravel is arranged at the top side of the star. Inthis way it can be obtained that the filling does not begin before the star has reached such a position that no parts can get jammed between the side wall and the partitions. Preferably the closing of the containers for the gravel or the sand, formed by the partitions of the star shaped dosage mechanism, in the direction of rotation is formed by hinged bat-Hes charged by a spring. The baflles can then at the same time serve as striking means for the containers, but if necessary they can give way for the passage of hard gravel parts projecting out of the contamer.

The invention will now be further elucidated with reference to the drawing in which an example of performance is shown.

In the drawing:

The Figures 1a and lb show a complete mixing machine according to the invention in side elevation and front elevation respectively,

The Figures 2a. and 2b show the dosage mechanism for the gravel or the sand in cross-section and longi- Itatuiii lnal section respectively, with feed hopper and striking The Figures 3a and 3b show the dosage mechanism for-the cement in top elevation and partly in cross sectron, and in side elevation and partly in longitudinal section respectively.

In the drawing 1 indicates the frame of profile iron on which a box 2 is fixed, containing the driving motor with the speed reduction mechanism consisting of chain wheels and chains. This mechanism drives, by means of a short main spindle 3 with a conical gear wheel, the vertical spindle 4 for the dosage of the cement and by the large conical gear wheel at the same time, with the aid of a chain 5, the small conveyor band 6 to which the dosage mechanisms deliver their materials and which brings the material to the mixing drum. The short main spindle 3 also drives, by means of a chain and chain wheels 7, the spindle 8 for the gravel dosage mechanism and the spindle 9 for the sand dosage mechanism. The spindle 8 is extended and carries at the end a chain wheel 10 for driving the mixing drum 12 by means of a chain lying round the chain wheel 10 and the chain wheel 11 on the spindle of the drum.

The drum 12 consists of a worm 13 of plate iron which is fixed to a spindle 14 and is driven by this spindle. At the outer circumference of the worm transverse ribs 15 (in the shown example sixteen ones) are arranged at regular distances for reinforcing purposes and at the same time for providing sufficient gripping surfaces for the endless rubber band 16 forming the proper wall of the drum.

The rubber band at the same time passes round a stretching roller 17 arranged above the drum. In the space between the drum and the stretching roller a scraper fillet 18 is arranged at the inside of the whole Width of the rubber band. By that the rubber band forms the wall of the drum, the upper part of it is always open. In this manner the mixed material therefore can never come higher than the scraper device, so that the mixture can never fall back in a preceding (wrong) helical passage. At the same time the scraper fillet provides for keeping the rubber band 10 clean in cooperation with the water supply pipe 19 mounted below it.

The cement passes through the hopper 20, the dosage mechanism 21 (Figures 3a and 3b) and falls on the conveyor band 6 lying under it.

The hoppers 22 and 23 serve for storing the sand and the gravel, which fall through the dosage mechanism 24 (Figs. 2a and 2b) simultaneously with the cement on the conveyor band 6, which deposes a continuous stream of the different materials into the mixing drum in the desired proportion.

The dosage mechanism for the cement (Figures 3a and 3b), which is driven by a vertical spindle, consists of a box-shaped member 25 in which a number (for instance twelve) radial pins 26 are arranged. Round these pins partitions or rectangular vanes 27 are rotatably arranged. They are provided at the inner end with a laterally cylindrical pin 28 arranged on a transverse arm, round which a spherical sleeve 29 is arranged. These spherical sleeves fit in cylindrical axial boring 30 in the member 31, which is rotatable with respect of the boxshaped member 25 and can be fixed to it by means to a clamping bolt 32. By turning the part 31 with respect to the part 25 the vanes or partitions 27 will assume another position whereby the contents of the compartments formed between these partitions can be altered as desired and at the same time the displacement of the cement per revolution. The mechanism for the dosage of the sand and the gravel, which is supplied through the hoppers 22 and 23, is shown in the Figures 2a and 2b, and consists of the spindle 8 and the spindle 9 respectively, which are driven by the chain 7 and on which a flange 33 is keyed and round which the member 34 is rotatably mounted. In this member the adjustable partitions 35 are arranged which are mounted rotatably on their journals 36 in the flanges of the member 34. One of the journals 36 of each partition is extended as a lever 37 and is connected with the flange 33 by means of the part 38.

By turning the flange 33 with respect of the member 34 the partitions 35 will assume another position so that the contents of the space formed between two partitions is altered and there with the delivery of the sand and the gravel respectively per revolution.

With the aid of the clamping bolt 39 the flange 33 can be fixedly connected with the member 34.

The hinged baffles 40 form the closing at the bottom side of the sand and the gravel hoppers in the direction of rotation of the dosage mechanisms. They serve at the same time as striking means and can give way when a gravel particle or something else would be jammed between one of the partitions and the baffle and they assume immediately afterwards the right position again, because they stand continuously under pressure of a spring. The tension of the spring is not greater than necessary for retaining the material.

In the shown example the drum is executed as a polygonal skeleton drum, arid the stretching roller as a cylindrical roller. However, it is also possible to make the drum as an externally round skeleton drum and the stretching roller as an externally polygonal skeleton drum. Further the dosage mechanisms can be arranged higher, whereby the supply conveyor 6 can be replaced by a chute. In this case appropriately a separate chute is used for the cement. The hoppers for the material are then removed from the dosage mechanisms and the dosage mechanisms are fed with the aid of conveyors.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed I declare that what I claim is:

l. A mixing machine for concrete and similar materials comprising separate sources of supply of gravel, sand and cement, a horizontally disposed mixing drum, means to feed the gravel, sand and cement into the mixing drum in predetermined quantities, further means to rotate said mixing drum, said drum including a skeleton framework forming a helical passage therein, a stretching roller supported above the skeleton framework, a flexible band passing around the perimeter of the framework and the roller defining the wall of the mixing drum with the drum being open intermediate the roller and the top of the framework, means cooperating with said band to maintain the band taut, and a water supply means communicating with the drum for mixing with the gravel, sand and cement.

2. Mixing machine according to claim 1, characterised in that the flexible band is defined by an endless conveyor band and a rubber covering thereon.

3. Mixing machine according to claim 1, characterised in that the space between the framework and the stretching roller, a scraper fillet is arranged extending axially the whole width of the drum and cooperating with the surface of the flexible band intermediate the framework and the roller.

4. Mixing machine according to claim 1, characterised in that in the space between the mixing drum and the stretching roller said water supply means is arranged which sprays the water against the surface of the flexible band intermediate the framework and the roller.

5. Mixing machine according to claim 4, characterised in that the water supply means is arranged in the direction of the movement of the flexible band below the scraper fillet.

6. Mixing machine according to claim 5, characterised in that the water supply means is defined as a spraying pipe lying in axial direction.

References Cited in the file of this patent UNITED STATES PATENTS 900,227 Svenson Oct. 6, 1908 1,622,294 Saulnier Mar. 29, 1927 2,499,162 Rand Feb. 28, 1950 2,537,585 Hilkemeier Jan. 9, 1951 

